| Ricki Osterthun | |
| Birth Date: | 1964 5, df=y |
| Birth Place: | Hamburg, West Germany |
| Plays: | Right-handed |
| Singlestitles: | 1 |
| Highestsinglesranking: | No. 58 (19 October 1987) |
| Australianopenresult: | 2R (1985) |
| Frenchopenresult: | 4R (1987) |
| Wimbledonresult: | 2R (1986, 1987, 1988) |
| Usopenresult: | 2R (1986, 1987, 1988) |
| Doublestitles: | 3 |
| Highestdoublesranking: | No. 67 (24 April 1989) |
| Australianopendoublesresult: | 2R (1990) |
| Frenchopendoublesresult: | 3R (1988) |
| Wimbledondoublesresult: | 2R (1988) |
Ricki Osterthun (born 2 May 1964) is a former tennis player from West Germany, who won one single title (1985, Hilversum) during his professional career.
The right-hander reached his highest singles ATP-ranking on 19 October 1987, when Osterhun became the number 58 of the world.
| Result | W–L | Date | Tournament | Surface | Partner | Opponents | Score | |
|---|---|---|---|---|---|---|---|---|
| Win | 1–0 | Jun 1987 | Athens, Greece | Clay | Jaroslav Navrátil Tom Nijssen | 6–2, 3–6, 6–2 | ||
| Win | 2–0 | Oct 1988 | Toulouse, France | Hard (i) | Mansour Bahrami  Guy Forget | 6–3, 6–4 | ||
| Win | 3–0 | Apr 1989 | Nice, France | Clay | Udo Riglewski | Heinz Günthardt  Balázs Taróczy | 7–6, 6–7, 6–1 |